Understanding systematic reviews : the meta-analysis graph (also called 'forest plot')

Mammographic screening for breast cancer is controversial, as reflected in greatly varying national policies. The objective was to assess the effect of screening for breast cancer with mammography on mortality and morbidity. MEDLINE (16 May 2000), The Cochrane Breast Cancer Group's trial register (24 Jan 2000) and reference lists. Letters, abstracts and unpublished trials. Authors were contacted. Randomised trials comparing mammographic screening with no mammographic screening. Data were extracted by both authors independently. Seven completed and eligible trials involving half a million women were identified. The two best trials provided medium-quality data and, when combined, yield a relative risk for overall mortality of 1.00 (95% CI 0.96-1.05) after 13 years. However, the trials are underpowered for all-cause mortality, and confidence intervals include a possible worthwhile effect as well as a possible detrimental effect. If data from all eligible trials (excluding flawed studies) are considered then the relative risk for overall mortality after 13 years is 1.01 (95% CI 0.99-1.03). The best trials failed to show a significant reduction in breast cancer mortality with a relative risk of 0.97 (95% CI 0.82-1.14). If data from all eligible trials (excluding flawed studies) are considered then the relative risk for breast cancer mortality after 13 years is 0.80 (95% CI 0.71-0.89). However, breast cancer mortality is considered to be an unreliable outcome and biased in favour of screening. Flaws are due to differential exclusion of women with breast cancer from analysis and differential misclassification of cause of death. The currently available reliable evidence does not show a survival benefit of mass screening for breast cancer (and the evidence is inconclusive for breast cancer mortality). Women, clinicians and policy makers should consider these findings carefully when they decide whether or not to attend or support screening programs

Measuring the Impact of Evidence : the Cochrane Systematic Review of Organised Stroke Care

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Human albumin solution for resuscitation and volume expansion in critically ill patients

BACKGROUND: Human albumin solutions are used in a range of medical and surgical problems. Licensed indications are the emergency treatment of shock and other conditions where restoration of blood volume is urgent, burns, and hypoproteinaemia. Human albumin solutions are more expensive than other colloids and crystalloids. OBJECTIVES: To quantify the effect on mortality of human albumin and plasma protein fraction (PPF) administration in the management of critically ill patients. SEARCH STRATEGY: We searched the Cochrane Injuries Group trials register, Cochrane Central Register of Controlled Trials, Medline, Embase and BIDS Index to Scientific and Technical PROCEEDINGS: Reference lists of trials and review articles were checked, and authors of identified trials were contacted. The search was last updated in August 2004. SELECTION CRITERIA: Randomised controlled trials comparing albumin/PPF with no albumin/PPF, or with a crystalloid solution, in critically ill patients with hypovolaemia, burns or hypoalbuminaemia. DATA COLLECTION AND ANALYSIS: We collected data on the participants, albumin solution used, mortality at the end of follow up, and quality of allocation concealment. Analysis was stratified according to patient type. MAIN RESULTS: We found 32 trials meeting the inclusion criteria and reporting death as an outcome. There were 1632 deaths among 8452 trial participants. For hypovolaemia, the relative risk of death following albumin administration was 1.01 (95% confidence interval 0.92-1.10). This estimate was heavily influenced by the results of the SAFE trial, which contributed 91% of the information (based on the weights in the meta-analysis). For burns, the relative risk was 2.40 (1.11-5.19) and for hypoalbuminaemia the relative risk was 1.38 (0.94-2.03). There was no substantial heterogeneity between the trials in the various categories (chi2 = 21.86, df = 25, p = 0.64). The pooled relative risk of death with albumin administration was 1.04 (0.95-1.13). CONCLUSIONS: For patients with hypovolaemia there is no evidence that albumin reduces mortality when compared with cheaper alternatives such as saline. There is no evidence that albumin reduces mortality in critically ill patients with burns and hypoalbuminaemia. The possibility that there may be highly selected populations of critically ill patients in which albumin may be indicated remains open to question. However, in view of the absence of evidence of a mortality benefit from albumin and the increased cost of albumin compared to alternatives such as saline, it would seem reasonable that albumin should only be used within the context of well concealed and adequately powered randomised controlled trial. PLAIN LANGUAGE SUMMARY: There is no evidence that giving human albumin to replace lost blood in critically ill or injured people improves survival when compared to giving saline. Trauma, burns or surgery can cause people to lose large amounts of blood. Fluid replacement, giving fluids intravenously (into a vein), is used to help restore blood volume and hopefully reduce the risk of dying. Blood products (including human albumin), non-blood products or combinations can be used. The review of trials found no evidence that albumin reduces the risk of dying. Albumin is very expensive in which case it may be better to use cheaper alternatives such as saline for fluid resuscitation